1. Field of the Invention
This invention provides a means of modifying the flow of air into a combustion apparatus. Specifically, it provides a means of modifying the location of the airflow within the apparatus.
2. Description of the Prior Art
Past practice has most commonly been to fix the location of an air supply within a combustion apparatus, and to provide a means of modifying the rate of airflow into the apparatus. This practice is especially well suited for use when the type of fuel and depth of fuel bed remain constant or nearly so.
One typical air supply arrangement furnishes primary combustion air at a certain depth below the top of the fuel bed, usually through a grate. Secondary air is supplied to the fire at a certain height above the top of the fuel bed. The depth of the primary air supply and the height of the secondary air supply are established so as to provide maximum efficiency at the design rate of burning. The fuel bed depth is maintained constant by a continuous fuel-loading mechanism.
When the type of fuel and/or depth of fuel bed are subject to change, a means of modifying the location of the airflow within the combustion apparatus is sometimes desirable. Several prior inventions provide such means; however, the present invention offers an original mechanism which is especially well-suited for certain uses, as should become apparent from the description below.